Microfluidic systems are becoming increasingly important in many application areas such as biotechnology, diagnostics, medical or pharmaceutical industries. Microfluidic systems also lead to a concept of lab-on-a-chip, which is the integration of an entire bio/chemical laboratory onto a single silicon or polymer chip.
For realizing such microfluidic systems, a driving force moves samples within microfluidic structures. Centrifugal force is one of the forces generated by rotating the microfluidic systems typically on a compact disc-shaped substrate. With a suitable design of microchannels, valves, vents, chambers, etc., the functions such as fluid transport, splitting, merging can be realized. See for example U.S. Pat. Nos. 6,527,432 7,061,594 and 7,141,416. However, the microfluidic structures and platforms disclosed therein are only for assays with reaction under room temperature. For functions such as DNA extraction, loop-mediated isothermal amplification and polymerase chain reaction, a higher temperate is needed. This requires temperature control components to be attached to areas of the microfluidic structures where temperature variation is needed. See for example U.S. Pat. Nos. 5,639,428 and 6,706,519, and European Patent Application EP 1,813,683 A1. However, the methods for changing the sample temperature disclosed therein are realized through changing the temperature of heating elements and heating areas of the microfluidic structure, which is time consuming.